This invention relates to a side impact protection device including a side impact carrier, and a fastening device for the side impact carrier on a motor vehicle door part, the fastening device having at least one console and a holding bolt which reaches through respective fastening openings in the console and an end section of the side impact carrier, as well as to a motor vehicle door having such a side impact protection device.
A side impact protection device of the initially mentioned type is known from German Patent Document DE 44 05 295 C1. This side impact device includes a side impact carrier as well as a fastening device for fastening the side impact carrier to a motor vehicle door frame. The fastening device comprises a console which is formed by an extension of the door frame. The fastening device also has a screw as a holding bolt which reaches through the console as well as an end section of the side impact carrier in fastening openings. The longitudinal axis of the holding bolt extends at a right angle with respect to the principal axis of inertia of the side impact carrier which is relevant in the event of a load (side impact). During a bending operation of the side impact carrier, bending forces are introduced into the console. Furthermore, when the side impact carrier is deflected, tensile forces occur which cause a relative displacement between the side impact carrier and the console. During the relative displacement, a ramp-type bevel has an effect on the console and on the side impact carrier, respectively, whereby tensile forces are built up in the direction of the longitudinal axis of the holding bolt. In the side impact protection device, the forces acting on the side impact carrier are directly transmitted into the fastening device with the holding bolt as well as the console and thus also into the motor vehicle door frame.
It is an object of the invention to provide a side impact protection device of the initially mentioned type and a motor vehicle door having such a side impact protection device in which the device has a simple design and, in particular, has a fastening device which is subjected to low stress in the event of a load.
This object is achieved by a side impact protection device as mentioned above in which at least one load-alleviating opening is constructed in the side impact carrier or in the console at a distance, viewed in a longitudinal range of the side impact carrier, behind at least one of the fastening openings, in which, as a deformation resistance, a material projection is situated between the at least one of the fastening openings and the load-alleviating opening so that, after deformation of the deformation resistance, the holding bolt can enter into the load-alleviating opening, and in which a longitudinal axis of the holding bolt extends approximately parallel to a principal axis of inertia relevant to a load of the side impact carrier, as well as by a motor vehicle door having a side impact protection device with such features. Additional characteristics further developing the invention are included in corresponding dependent claims.
Principal advantages achieved by the invention include that, in the event of a load during a side or pole impact, after deformation of the deformation resistance (desired breaking point), the side impact carrier is guided with its load-alleviating opening over the holding bolt at the console, and the connection point between the console and the side impact carrier is therefore subjected to a lower stress. A further rise of the tensile forces in the motor vehicle door part is thereby prevented. During the bending strain as a result of the side impact, the side impact carrier can move relative to the console without introducing relevant moments or forces by way of the holding bolt into the console. Lower moments therefore have to be compensated for in the console and thus in the motor vehicle door part. In addition, the side impact protection device according to the invention is distinguished by a simple construction which, in contrast to the state of the art, requires no additional parts.
The deformation resistance can be formed by a tearing web which is continuous and which separates the fastening opening from the load-alleviating opening and represents the desired breaking point. As an alternative, the fastening opening and the load-alleviating opening can be implemented as a joint opening which has a keyhole-type contour, so that the deformation resistance is present in the transition area between the two hole sections.
In a preferred embodiment, the load-alleviating opening is constructed as an elongated hole which extends in the direction of the longitudinal range of the side impact carrier, so that, after the deformation resistance is overcome, the side impact carrier can be elongated without correspondingly introducing tensile forces into the holding bolt or the console and thus into the door part.
In another embodiment, several load-alleviating openings can be arranged behind one another, between which, in each case, another tearing web or a deformation resistance is situated. The tearing webs are each used as a desired breaking point when, as a result of the elongation of the side impact carrier, correspondingly high tensile forces are present between the holding bolt and the corresponding tearing web. As a result, the introduction of force into the door part can be controlled.
If the width of the load-alleviating opening is larger than the outside diameter of the holding bolt, then, after the tearing web fails, the side impact carrier can place itself against the console. The motor vehicle door part is therefore loaded in an essentially moment-free manner and has to absorb mainly supporting forces.
In another embodiment, the elongated hole can narrow in a hole section facing away from the fastening opening, specifically such that the width in this hole notch is, at least in areas, smaller than the outside diameter of the holding bolt. Consequently, although moments/forces are introduced into the door part, the bending strain of the side impact carrier and thus the penetration depth of an object during the side impact can be influenced.
In certain embodiments, it is advantageous that, after deformation of the deformation resistance, the side impact carrier can place itself against the console and absorb the supporting forces.
In the following, embodiments of the invention will be explained in detail with reference to the drawings.